The present invention relates to an information retrieval control system, and in particular, to an information retrieval control system of a database machine system in which retrieval processing is achieved in synchronism with a data item read from a rotating recording medium, such as a disk device.
The conventional information retrieval control system using hardware control has been described in the ACM Transactions on Database Systems, Vol. 9, No. 2, June 1984, namely, "A Parallel Pipelined Relational Query Processor" by Won Kim, Daniel Gavid, and David J. Kuck. A queue processor discussed in this literature comprises only four processing pipes and a plurality of random access memory (RAM) modules. It has been described that each pipe is designed to process a relational tuple (logical record) in a bit-serial fashion and a parallel processing is executed on the relational tuple for each primitive database operation constituting a composite relational queue.
However, this description assumes that all data read is correct. Actually, there exist errors in the obtained data, although the number thereof is quite small. In this regard, for example, an important processing to be effected in a case where a data error is found in the data read from a disk unit has not been discussed. Moreover, a method for acquiring the relative position and the length of an attribute has not been described.